A known superconducting apparatus is disclosed in JP2006-238570A (which will be hereinafter referred to as Reference 1). The superconducting apparatus disclosed in Reference 1 includes a rotor on which a superconducting coil is mounted. The rotor is arranged within a heat insulation container of which a bottom portion is filled with liquid nitrogen serving as a refrigerant. According to the superconducting apparatus disclosed in Reference 1, a lower portion of the rotor is immersed in the refrigerant so that the refrigerant disperses within the heat insulation container by means of a rotation of the rotor.
In addition, another known superconducting apparatus is disclosed in JP2007-89345A (which will be hereinafter referred to as Reference 2). The superconducting apparatus disclosed in Reference 2 includes a conductive cooling mechanism that is maintained at an extremely low temperature by a refrigerator. A superconducting coil mounted on a stator is cooled through a conductive cooling by the conductive cooling mechanism.
According to each of the aforementioned superconducting apparatuses disclosed in References 1 and 2, an external heat may be transmitted to the superconducting coil via a feed terminal in a case where a driving of the superconducting apparatus is stopped, which may lead to a temperature increase of the superconducting coil.
A need thus exists for a superconducting apparatus which is not susceptible to the drawback mentioned above